Some display apparatuses may display information in an appropriate output format by controlling the output format of display information displayed on a display surface according to an apparatus orientation detected using an acceleration sensor or the like. For example, the apparatus orientation is represented by the relative relationship between the direction of the display surface and the direction of gravity. In this case, for example, when the display surface becomes substantially parallel to the direction of gravity, the display apparatus aligns the direction of display information with the direction of gravity to thereby display the display information so as to be readily visible to a user.
However, if the output format of display information is fully automatically controlled in such a display apparatus as described above, inconvenience may occur.
For example, consider a case in which the direction of display information is aligned with the direction of gravity. In this case, when the user lies on a sofa or a bed with the face oriented in a horizontal direction, the direction is such that the display information is not well visible to the user. In addition, consider a case in which the user uses the display apparatus with the display surface oriented in a horizontal direction such as when a map is displayed or when the user looks at the screen together with other people. In this case, only a slight tilt of the display apparatus by the user may change the direction of display information. In addition, consider a case in which the user temporarily puts the display apparatus held by the hand on a desk or the like and then picks it up. Each operation of putting and picking up the display apparatus may change the direction of display information.
Alternatively, there can be considered a display apparatus that represents the apparatus orientation not by a relative relationship between the direction of the display surface and the direction of gravity but by a relative relationship between the direction of the display surface and the direction of the user's face. In this case, the display apparatus changes the output format of display information according to the direction of the user's face detected, for example, by a camera or the like. However, in the case in which the output format of display information is fully automatically controlled, if the camera detects a plurality of user's faces, the output format is frequently changed, and thus even such a display apparatus may cause the user to be annoyed.
As described above, such a display apparatus that fully automatically controls the output format of display information has a problem of causing inconvenience.
As a technique capable of solving the above problem, there can be considered a technique for allowing the user to select whether or not the output format of display information is automatically controlled. However, such a technique requires the user to preset whether or not the output format of display information is automatically controlled or not, which is inconvenient to the user.
Alternatively, there can be considered a display apparatus that does not change the direction of display information if the apparatus orientation is changed while a predetermined key is being pressed. However, such a display apparatus does not allow the user to change the direction of display information by an intuitive operation, but requires the user to learn key functions, which is inconvenient to the user.
In view of this, Patent Literatures 1 and 2 disclose a technique that allows the user to change the direction of display information by intuitive operation using a touch panel. Even if the direction of display information is inappropriate, this technique allows the user to change the direction of display information to an appropriate direction by intuitive operation.